Can this planet have an ocean of water?

In summary, an ocean of this size could exist on a planet with an atmospheric pressure of 0.10 bar/10%
  • #1
willstaruss22
108
1
Lets say there is an exoplanet with 0.5 Earth masses and is 0.8 Earth radii. This planet has an atmospheric pressure of 0.10 bar/10% as thick as Earths atmosphere with an average surface temperature of 285 K. Can this planet have a body of liquid water the size of an ocean with the low atmospheric pressure?
 
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  • #2
Saturation pressure at that temperature is ~16mbar, a significant fraction of your atmosphere would be H2O.

The escape velocity at the surface is roughly 10km/s. This is similar to earth, indicating that the lifetime of the atmosphere is similar as well. Some hydrogen will be lost, but water can be present for billions of years. A magnetic field can help against solar wind, but it is not necessary, as Venus shows.
 
  • #3
So how large a fraction are we talking, over 10 of the total mass of the atmosphere?
Could an ocean as large as the Indian Ocean exist?
 
  • #4
willstaruss22 said:
So how large a fraction are we talking, over 10 of the total mass of the atmosphere?
You gave the volume fraction on surface. 285 K means 16 mbar saturated water vapour. Since the total is 100 mbar, it means 84 mbar is other gases.

This is the volume fraction. What the mass fraction is depends, on surface, what the molecular mass of the other gases is. Total mass of the atmosphere, depends also on the climate. The upper levels of atmosphere will be less than 16 % water, because some will rain or snow back down, but exactly how much less depends on the details of atmospheric composition and climate.

willstaruss22 said:
Could an ocean as large as the Indian Ocean exist?

Sure. An ocean bigger than Pacific could also exist. The water fraction is arbitrary, in a wide range.
 
  • #5
Well my planet will have 73% nitrogen, 8% oxygen and 2% Co2 factoring the 16% water vapor. I was kind of going for simple life that is resistant to solar radiation producing oxygen in the atmosphere. I was expecting there to be 50% land 50% water on the planet.
 
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  • #6
I was expecting there to be 50% land 50% water on the planet.
Should be fine.
The density is slightly higher than Earth's, indicating more heavy elements, and probably more radioactive decays in the core. It looks like plate tectonics is possible.

If oxygen is produced, something (living or not) should consume oxygen again.
 
  • #7
Now as far as rotation is was going for 12 hours and going for a tilt of 28 degrees but I am not sure how the climatic condition of these two will act in a 0.10 atmosphere. My thinking is the shorter days will even up the temperature differences to an extent and that the more extreme tilt will even the difference between the equator and poles.
 
  • #8
More tilt will lead to more extreme seasons at the poles, in addition to the colder climate there.
 
  • #9
Ok so do you think that with the conditions presented the liquid oceans could last a few billion years?
 
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  • #10
Mars, with 0,1 Earth masses, had running rivers, and probably oceans, for a long time. It seems likely that a planet slightly more massive than Mars could keep its water.
 
  • #11
Ok so you said that there could be an ocean the size of the pacific ocean on this planet. So here is a question what about a global ocean with no land at all still keeping the atmospheric pressure at 0.10? I have heard that regular oceans and seas can exist in liquid form with a atmosphere like this so what about a total global ocean?
 
  • #12
There is no limit on the size of the ocean (well, it cannot cover more than 100% of the surface :p). This is independent of the atmosphere - if oceans are possible, their size is not restricted.
 

1) Can this planet have an ocean of water?

This is a common question in the search for habitable exoplanets. The answer depends on the planet's size, distance from its star, and composition. If the planet is within the habitable zone and has a similar composition to Earth, then it is possible for it to have an ocean of water.

2) How do scientists determine if a planet has an ocean of water?

Scientists can use various methods, such as transit observations, to detect the presence of water on a planet. They can also analyze the planet's atmospheric composition and look for the presence of water vapor.

3) Can a planet have too much water to sustain life?

Yes, a planet can have too much water to sustain life. This is known as a "water world" and it is not hospitable for life as we know it. The high pressure and lack of landmasses make it difficult for complex organisms to thrive.

4) What other factors besides water are important for a planet to sustain life?

Water is essential for life, but other factors such as a stable atmosphere, a suitable temperature range, and the presence of organic molecules are also important. The planet's distance from its star, the type of star, and the planet's geological activity also play a role in its habitability.

5) Is it possible for a planet to have multiple oceans of water?

Yes, it is possible for a planet to have multiple oceans of water. Earth, for example, has five major oceans. Other factors such as tides and the planet's rotation can also affect the distribution of water on a planet's surface.

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